Yamanaka K, Hwang J, Inouye M
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
J Bacteriol. 2000 Dec;182(24):7078-82. doi: 10.1128/JB.182.24.7078-7082.2000.
A gene encoding a putative GTP-binding protein, a TrmE homologue that is highly conserved in both prokaryotes and eukaryotes, was cloned from Thermotoga maritima, a hyperthermophilic bacterium. T. maritima TrmE was overexpressed in Escherichia coli and purified. TrmE has a GTPase activity but no ATPase activity. The GTPase activity can be competed with GTP, GDP, and dGTP but not with GMP, ATP, CTP, or UTP. K(m) and k(cat) at 70 degrees C were 833 microM and 9.3 min(-1), respectively. Our results indicate that TrmE is a GTP-binding protein with a very high intrinsic GTP hydrolysis rate. We also propose that TrmE homologues constitute a novel subfamily of the GTPase superfamily.
从嗜热栖热菌（一种超嗜热细菌）中克隆出一个编码假定GTP结合蛋白的基因，该蛋白是TrmE的同源物，在原核生物和真核生物中都高度保守。嗜热栖热菌TrmE在大肠杆菌中过量表达并纯化。TrmE具有GTP酶活性，但没有ATP酶活性。GTP酶活性可被GTP、GDP和dGTP竞争，但不能被GMP、ATP、CTP或UTP竞争。70℃时的米氏常数（K(m)）和催化常数（k(cat)）分别为833微摩尔和9.3分钟-1。我们的结果表明，TrmE是一种具有非常高的内在GTP水解速率的GTP结合蛋白。我们还提出，TrmE同源物构成了GTP酶超家族的一个新亚家族。
